The bug
Currently when an anvil falls on any non-full block (such as a redstone wire, button, torch, skull, etc.) it drops as item.
In previous versions it used to replace some of them, however did not drop them as item, see also MC-98997.
Attachments
Comments

[media][media]
This issue relates to MC-1511 / MC-98997 / MC-838 / MCPE-21623.
And relates or duplicates to MC-5614.

Reworded the description a little bit, I hope you are fine with that.